In his fifth year at Hogwarts, Severus Snape forges a friendship with a Slytherin girl, Charlotte Rosier, sister to Death Eater Evan Rosier, all the while pining for Lily Evans. The two connect intellectually and emotionally, setting off a chain of events that leads to enlightenment, but also to the darkest magic and war.

This is an alternate version of Book Seven. Harry reluctantly returns to Hogwarts to train with a new DADA teacher, one appointed in specifically for Harry in Dumbledore's will. As the rest of the Wizard World reacts to Dumbledore's defeat, Harry develops the skills he needs to fulfill the Prophecy--including mastery of the Kedavra curse.

Mysteries are explored along the way, particularly the "missing 24 hours" from 1981--the span of time between Hagrid taking Baby Harry from the ruins of Godric's Hollow on Halloween Night, and his arrival to hand off Baby Harry on Privet Drive the following night. The Veil Room in the Department of Mysteries is also revisited. A traitor is uncovered, and Dumbledore's wisdom comes into question. And even when all goes as planned, things are not all they seem.

As the Marauders enter their seventh and final year at Hogwarts, the outside world explodes in war, violence, and hatred. There are rumours, some say, of a secret resistance, determined to fight Lord Voldemort's ever-growing army. The boys make a pact: they will find and join the resistance, and do whatever it takes to fight the forces of evil that threaten to tear the Wizarding world apart. However, little do they realize, the resistance is already at Hogwarts, right under their noses. Lily/James, Sirius/Remus, Alice/Frank.

The final pairings of Remus and Nagini, and Severus against Sirius, in the Dark Arts competition for the Young Wizards Merit Award during their sixth year, gets out of hand. Unexpectedly, from this one event, their lives become intertwined, changed forever. Nagini, the main female character, is actually a precursor to Voldemort's serpent, Nagini.